The present invention relates to a thermal energy conversion device, a unit having the device, and a thermal energy conversion method, and more particularly, relates to the configuration of a thermal energy conversion device for deriving energy based on changes in pressure or volume of heating medium due to changes in temperature.
A table clock called xe2x80x9cAtmosxe2x80x9d from Jaeger-LeCoultre is known as a timepiece in which dynamic energy is obtained by using changes in outside air temperature. Inside this table clock, a deformable sealed container is placed so as to contain ethyl chloride as heating medium in a state which is a mixture of a gaseous phase and a liquid phase. When the internal pressure of the sealed container is changed due to a change in temperature, the sealed container is deformed, and a mainspring is wound up by the deformation, thereby storing energy for driving pointers.
In contrast, techniques for obtaining driving energy for a timepiece by converting thermal energy into dynamic energy in response to a change in ambient temperature, in a manner similar to that of the above-described table clock, are disclosed in, for example, Japanese Unexamined Patent Applications Publication Nos. H6-341371 and H10-14265. Both of these techniques adopt a structure in which liquid and gas are contained as heating media in a sealed container having an expandable bellows, and a driving lever is connected to the sealed container. When the sealed container expands and contracts in response to changes in outside air temperature, the driving lever also moves reciprocally, and rotational motion is generated by a gear meshed with the driving lever. When the rotational motion is transmitted to a rotor of a power generator either directly or via a mainspring or the like, power is generated in the power generator. The generated electrical energy is then stored in a capacitor, a secondary battery, or the like.
In the above techniques, however, since the temperature of outside air generally changes relatively slowly, deformation of the sealed container is considerably slow. As a result, it is difficult to efficiently derive dynamic energy from the deformation of the sealed container.
That is, in the above-described table clock, Atmos, since a coil spring for pressing the sealed container has great elastic force and since the amount of deformation of the sealed container is limited in order to improve pressure resistance of the sealed container, it is impossible to respond to a sudden change in outside air temperature. Moreover, it is also impossible to derive energy from slight changes in the outside air temperature.
In the techniques described in the above publications, in order to efficiently convert thermal energy, deformation of the sealed container is restrained until the outside air temperature changes by some amount, and the restraint force is suddenly released when the amount of change in temperature exceeds a predetermined value, thereby rapidly and greatly deforming the sealed container so as to generate dynamic energy. In this case, it is possible to improve energy conversion efficiency of the power generator, whereas, when rapid increase and decrease in temperature are caused (for example, when the temperature rises rapidly and then falls rapidly), the temperature returns to its initial temperature before the sealed container is released. This does not allow dynamic energy to be obtained. In a case in which the temperature changes slowly, it takes a considerably long time before deriving of thermal energy is started. Furthermore, when the temperature rises and falls before thermal energy can be derived, even if heat is conducted into and out of the sealed container with the rise and fall of the temperature, dynamic energy cannot be derived based on the movement of the heat. Therefore, in the conventional methods, most of the energy, which is supposed to be obtained, cannot be derived and is lost.
The present invention aims to solve various problems in the above-described techniques.
That is, an object of the present invention is to provide a device or method which allows energy in an available form to be quickly or reliably derived even based on a slow temperature change, such as a change in air temperature.
Another object of the present invention is to provide a device or method which can satisfactorily respond to a rapid change in ambient temperature and which can reliably derive energy even when a temperature rise and a temperature fall are almost simultaneously caused within a short period.
A further object of the present invention is to provide a device or method which is highly responsive to various manners of change in ambient temperature and which can efficiently derive energy, for example, which can derive energy with high efficiency over a wide range of rates of change in ambient temperature.
In order to overcome the above problems, a thermal energy conversion device of the present invention includes: a heat converter having a sealed container for containing a heating medium which changes in volume in response to a change in temperature, said sealed container having a medium containing portion, which does not substantially change in capacity, and a variable portion connected to the medium containing portion so as to change in capacity; and an operating portion to be operated in response to a change in capacity of the variable portion. According to the present invention, since the variable portion capable of changing in capacity is connected to the medium containing portion, which does not substantially change in capacity, in the heat converter, when heat is exchanged between the heating medium in the medium containing portion and the outside, the volume of the heating medium changes and causes a change in capacity of the variable portion. In this case, since the medium containing portion does not substantially change in capacity, operations brought about by the capacity change of the heating medium in the medium containing portion are concentrated on the variable portion. This substantially changes the capacity of the variable portion. As a result, it is possible to sensitively and quickly deform the variable portion in response to a considerably slow and slight temperature change, such as a change in ordinary outside air temperature, and in response to a rapid temperature change caused when the device is moved from indoors to outdoors and is returned again to indoors, or when the device is placed out of close contact with the skin and is then put into close contact therewith again, thereby deriving dynamic energy of the operating portion from the deformation. This allows greater energy to be derived than was possible previously. Since a large amount of change in capacity of the variable portion is ensured even when operation thereof is not temporarily restrained, as described in the above publications, or even when the range of change in temperature for limiting the operation is reduced (a set value of the temperature range (temperature difference) for removing the restraint of operation is decreased), it is possible to efficiently derive energy.
In the above heat converter, the description xe2x80x9cthe capacity of the medium containing portion does not substantially changexe2x80x9d means that the capacity of the medium containing portion may be changed to a lower degree than that of the variable portion which changes in capacity in response to the change in volume of the heating medium. The above operating portion refers to a portion that is operated in response to a change in capacity of the variable portion, and refers to all the operating portions mechanically connecting the variable portion and a storage means for storing dynamic energy of the operating portion when the storage means is connected to the operating portion. Therefore, the operating portion may be formed of a single component or a plurality of connected members.
Alternatively, the medium containing portion and the variable portion may be separately formed and be connected to each other, or may be integrally formed. In a case in which the medium containing portion and the variable portion are integrally formed, for example, the medium containing portion may be formed so that it is thick and so that its volume does not substantially change even when the volume of the heating medium contained in the medium containing portion increases or decreases with temperature. In contrast, the variable portion may be formed so that it is thin and so that it is easily changed in capacity and deformed by the increase or decrease in volume of the heating medium.
The medium containing portion may be made of any material that is substantially rigid and has a high thermal conductivity. For example, an aluminum alloy, a copper alloy, a silver alloy, a gold alloy, and the like, which will be described later, are preferable. The variable portion may be made of any material that is likely to change in capacity in response to expansion or contraction of the heating medium due to a temperature change. For example, highly elastic materials, such as rubber, plastic, and a thin elastic metal, which will be described later, are preferable.
The heating medium may be any material that expands or contracts and changes in volume due to a change in temperature. In general, it is preferable that the heating medium be a substance which is in a gas phase or a liquid phase at ordinary temperatures and at ordinary pressures. For example, ammonia, carbon dioxide, and ethylene chloride are preferable. Oxygen, nitrogen, and air may also be used. Alternatively, the heating medium may be an elastic solid which is substantially deformed due to changes in temperature, or be a substance containing a mixture of at least more than two of a gas, a liquid, and a solid.
It is preferable that the surface of the medium containing portion be uneven. Since the surface area of the medium containing portion is increased by having such an uneven form, heat exchange between the heating medium and the outside is promoted. The heat exchange can be further promoted by forming a through portion penetrating the medium containing portion.
In the present invention, it is preferable that the capacity of the variable portion be less than that of the medium containing portion. Since the amount of change in capacity (amount of deformation) of the variable portion can be further increased by setting the capacity of the variable portion to be less than that of the medium containing portion, it is possible to further improve responsivity to temperature changes and to improve sensitivity to temperature changes.
In the present invention, it is preferable that the medium containing portion be extended. Since the ratio of the surface area of the medium containing portion to the capacity can be increased by making the medium containing portion extended, it is possible to increase the amount of heat conducted into and out of the medium containing portion and to further improve responsivity and sensitivity to a temperature change. In this case, it is particularly preferable to use a pipelike (tubular) medium containing portion. In order to make the medium containing portion compact, it is preferable that the outer surface of the extended medium containing portion have a dense integrated structure.
In the present invention, it is preferable that the extended medium containing portion be curved. Since the extended medium containing portion is curved, the device can be made compact, and the medium containing portion can be formed in an appropriate shape in accordance with the structure of the device and the like. This makes it possible to flexibly respond to various arrangement circumstances and to allow applications to small devices and portable devices. In this case, in particular, in a case in which the medium containing portion is pipelike (tubular), it is preferable that the medium containing portion be wound. In order to make the medium containing portion compact, it is preferable that the outer surface of the extended medium containing portion be provided with a dense integrated structure by curving the extended medium containing portion.
In the present invention, it is preferable that the variable portion protrude from the medium containing portion and that the sectional area of the variable portion taken along a plane orthogonal to the protruding direction of the variable portion be less than the sectional area of the medium containing portion taken along the plane in an area connected to the variable portion. In other words, it is preferable that the sectional area taken along a plane orthogonal to a direction from the medium containing portion toward the variable portion be reduced in the medium containing portion. When the variable portion protrudes outward from the medium containing portion and the sectional area thereof is less than that of the medium containing portion, it is possible to further increase the amount of deformation of the variable portion based on a change in volume in the protruding direction and to further increase the amount of dynamic energy to be transmitted to the operating portion. In this case, in order to increase the amount of energy to be derived, it is more preferable that the variable portion be deformable (or expandable) only in the above protruding direction.
In the present invention, it is preferable that the variable portion be expandable in a predetermined direction and that the operating portion be reciprocally movable in the predetermined direction in response to expansion and contraction of the variable portion. When the variable portion is expandable in a predetermined direction and the operating portion is reciprocally movable in the predetermined direction, dynamic energy generated by deformation of the variable portion due to a change in capacity can be derived only in the predetermined direction. This makes it possible to increase the operation stroke of the operating portion and to thereby derive energy more efficiently.
In the present invention, it is preferable to further include a storage means for storing the dynamic energy of the operating portion. In this case, it is preferable that the storage means store the dynamic energy of the operating portion after converting the dynamic energy into another form of energy. In a case in which the operation manner of the operating portion is not suited to continuous supply of energy, energy derived from the operating portion is stored in the storage means, and the stored energy can be thereby continuously supplied. The storage means includes a means for storing dynamic energy after converting the dynamic energy into strain energy of an elastic member, such as a mainspring, a coil spring, or a torsion spring, a means for storing dynamic energy after converting the dynamic energy into potential energy in accordance with the raised position of a weight or the like, a means for storing dynamic energy after converting the dynamic energy into rotation moment of a rotating member, such as a flywheel, and a means for storing dynamic energy after converting the dynamic energy into electrical energy by using a power generator or a piezoelectric device.
In the present invention, it is preferable that the storage means have a first storage portion for temporarily storing dynamic energy of the operating portion, and a second storage portion for converting and storing the energy output from the first storage portion. Dynamic energy of the operating portion to be operated in response to a change in capacity of the variable portion is converted and temporarily stored in the first storage portion, and the energy output from the first storage portion is stored again in the second storage portion. This makes it possible to temporarily store energy in the first storage portion, which is responsible to the operation manner of the operating portion or is suited to the operation manner of the operating portion with respect to conversion efficiency, even when the operation manner of the operating portion does not readily improve the efficiency of energy conversion, for example, when the action of the operating portion produced by a change in ambient temperature is irregular, or when the amount of action substantially varies with time, and to store the energy output from the first storage portion after converting the energy again into a desired form of energy or a more available form of energy. This allows both improvement of energy deriving efficiency and broadening of the range of choice of forms of energy.
In the present invention, it is preferable that the change in energy conversion efficiency of the first storage portion with respect to the amount of input energy be gentler than that of the second storage portion. When the change in energy conversion efficiency of the first storage portion with respect to the amount of input energy is gentler than that of the second storage portion, it is possible to respond over a broad range to an increase in amount of input energy due to a rapid temperature change and a decrease in amount of input energy due to a slow temperature change, and to improve energy deriving efficiency. Furthermore, the range of choice of means for converting and storing energy can be extended by converting the energy again by the second storage portion.
In the present invention, it is particularly preferable that the energy conversion efficiency of the first storage portion with respect to a small amount of energy be higher than that of the second storage portion. Since ordinary changes in ambient temperature are considerably slow in general, the amount of energy to be input to the first storage portion is also considerably small in ordinary cases. Even a small amount of energy can be continuously converted and stored by using the first storage portion having a high conversion efficiency for a small amount of energy, and this can increase the total amount of energy which can be derived.
For example, in the power generator for converting dynamic energy into electrical energy, manageable energy can be obtained, whereas the energy conversion efficiency rapidly decreases when the amount of dynamic energy to be input decreases. In contrast, in a case in which the mainspring is wound up by input energy, mechanical loss is inevitable, whereas the conversion efficiency can be maintained even when a small amount of input energy is applied.
In the present invention, it is preferable to further include a control means for controlling the amount of energy to be fed from the first storage portion to the second storage portion. Since the amount of energy to be fed from the first storage portion to the second storage portion can be controlled by the control means, the amount of energy to be temporarily stored in the first storage portion and the energy conversion speed of the second storage portion can be adjusted, as necessary. Therefore, for example, the energy conversion efficiency of the overall device can be improved by controlling the amount of energy to be fed from the first storage portion within the range of feeding speeds that allow a superior energy conversion efficiency of the second storage portion. In a case in which there is provided a working section (energy consuming portion) for consuming the energy stored in the second storage portion, only energy necessary for the working section can be fed to the second storage portion to be converted. Furthermore, in a case in which the working section for consuming energy is placed between the first storage portion and the second storage portion, the operating state of the working section can be controlled by controlling the amount of energy to be fed from the first storage portion to the second storage portion.
In the present invention, it is preferable that the control means control the feeding amount so as to reduce changes in the amount of energy to be stored in the second storage portion and that the second storage portion be connected to an energy consuming portion for consuming the energy stored in the second storage portion. When changes in amount of energy to be stored in the second storage portion are reduced by the control means, the first storage portion has an effective buffer action in the flow path of energy to the energy consuming portion. For example, the amount of energy stored in the second storage portion increases or decreases in accordance with the amount of energy consumed by the energy consuming portion, and, according to the increase or decrease, the amount of energy to be fed from the first storage portion to the second storage portion decreases or increases. Therefore, in a case in which there is a limit to the amount of energy to be stored in the first storage portion and the second storage portion, energy storage ability of the overall system can be efficiently used, and the amount of energy which can be derived by the overall system can be substantially increased.
In the present invention, it is preferable that the control means exert control so that the feeding amount is constant. When control is exerted so that the amount of energy to be fed from the first storage portion to the second storage portion is constant, it is possible to carry out stable energy conversion in the second storage portion and to thereby efficiently derive energy. For example, the amount of practically available energy can be increased by setting the energy feeding amount in accordance with the conversion speed that allows the highest energy conversion efficiency of the second storage portion.
In a case in which a driven portion for consuming energy is placed between the first storage portion and the second storage portion and is driven in an operation manner in accordance with the feeding amount of energy, the working state (operation manner) of the driven portion can be maintained constant by controlling the amount of energy to be fed from the first storage portion to the second storage portion. Accordingly, it is possible to construct a timepiece having a pointer as the driven portion, in which energy is transmitted from the first storage portion to the second storage portion at a constant rate of rotation.
In the present invention, it is preferable that the first storage portion be a mechanical energy storage means for converting dynamic energy of the operating portion into mechanical energy, such as strain energy, potential energy, or rotational energy, and temporarily storing the converted energy, and that the second storage portion have a power-generating means for converting energy output from the first storage portion into electrical energy and a storage means for storing the electrical energy obtained from the power-generating means. The first storage portion may include a means for storing dynamic energy after converting the dynamic energy into elastic strain energy by using an elastic member, such as a mainspring, a coil spring, or a torsion spring, a means storing dynamic energy after converting the dynamic energy into potential energy of a weight, and a means for storing dynamic energy after converting the dynamic energy into rotation moment by using a flywheel or the like. The second storage means may include a means, such as a power generator or a piezoelectric device, for storing energy after converting the energy into electrical energy.
The above-described thermal energy conversion device of the present invention is applicable to various devices. In various devices having a working section for consuming energy, a change in capacity of a variable portion connected to a medium containing portion caused by a change in ambient temperature is derived as dynamic energy of an operating portion, and the working section can be driven by using the energy in an unchanged form or after being appropriately converted into another form of energy. Examples of the devices are electronic devices to be operated by electrical energy converted from thermal energy, timepieces directly utilizing dynamic energy converted from thermal energy, and timepieces to be driven by using electrical energy converted from thermal energy. While portable devices require a battery or the like as an energy source, the use of the present invention can eliminate the need for an energy source itself, or can eliminate the need to replace the energy source by appropriately resupplying energy to the energy source.
In the present invention, it is preferable that a case member be provided to house the thermal energy conversion device and that the medium containing portion be placed along the inner surface of the case member. Components other than the thermal energy conversion device may be housed in the case member, as necessary. Since heat can be efficiently exchanged between the medium containing portion and the case member by placing the medium containing portion along the inner surface of the case member, it is possible to improve responsivity and sensitivity to changes in ambient temperature.
In the present invention, it is preferable that the case member and the outer wall of the medium containing portion be in close contact with each other or be integrally formed. When the case member and the outer wall of the medium containing portion are in close contact with each other or are integrally formed, heat can be more efficiently exchanged between the medium containing portion and the outside. This further improves responsivity and sensitivity to changes in ambient temperature. It is preferable that the surface in close contact with the case member or the outer wall formed integrally with the case member be uneven so as to increase the contact area (the area in close contact) or the surface area. When the close contact surface is uneven, it is preferable that the medium containing portion and the case member be engaged with each other through the uneven surface.
In the present invention, it is preferable that the case member be provided with a heat path extending from the outer surface of the case member to a position facing the medium containing portion and having a higher thermal conductivity than that of other portions. Since heat is conducted in and out preferentially through the heat path having a high thermal conductivity in the medium containing portion, thermal energy can be selectively derived by contacting the outer surface of the case member having the heat path with a specific heat source (e.g., the outside air). In a portable device such as a wristwatch, or in an accessory jewelry or the like), it is preferable that the heat path extend from a portion of the outer surface of the casing member of the device, other than the portions in contact with the body and clothing, which is exposed to outside air, toward the medium containing portion.
In the present invention, it is preferable that the case member selectively have an uneven shape on a portion of the outer surface facing the medium containing portion. Since an uneven shape is selectively provided on a portion of the outer surface of the case member facing the medium containing portion, the surface area of the case member is selectively increased at the portion of the outer surface. This allows heat to be conducted into and out of the medium containing portion preferentially through that portion.
In the present invention, it is preferable that a portion of the case member adjacent to the medium containing portion selectively have a heat-insulating portion having a lower thermal conductivity than that of other portions. When the heat-insulating portion is selectively formed, heat exchange between the medium containing portion and the outside is hindered at the portion with the heat-insulating portion. Therefore, in a case in which a portion of the outer surface of the case member is in contact with a heat source, which barely change in temperature, changes in temperature of the medium containing portion are prevented from being restrained by the thermal influence of the portion, and the amount of energy to be derived is prevented from being reduced. For example, in the case of a portable device such as a wristwatch, or an accessory jewelry or the like), changes in temperature of the medium containing portion can be prevented from being hindered by the influence of body heat, clothing, and the like by selectively forming a heat-insulating portion in a part of the case member in contact with the body and clothing.
In a thermal energy conversion method of the present invention, a heat converter is formed so as to have a sealed container for containing a heating medium that changes in volume in response to a temperature change, and the sealed container has a medium containing portion that does not substantially change in capacity and a variable portion connected to the medium containing portion so as to be changeable in capacity. A change in volume is caused in the variable portion by changing the internal temperature of the medium containing portion based on a change in outside air temperature, and dynamic energy is generated by the change in volume.
In another thermal energy conversion method of the present invention, a heat converter is formed to have a sealed container for containing a heating medium that changes in volume in response to a temperature change, and the sealed container has a medium containing portion that does not substantially change in capacity and a variable portion connected to the medium containing portion so as to be changeable in capacity. A change in volume is caused in the variable portion by shifting the medium containing portion from a state in which it is in thermal contact with a first heat source to a state in which it is in thermal contact with a second heat source having a different temperature from that of the first heat source, and dynamic energy is generated by the change in volume.
For example, in a case in which a portable device, an accessory (for example, jewelry), or the like having the heat converter therein is worn, the medium containing portion is in thermal contact with the body, clothing, or the like (first heat source). When the portable device, the accessory, or the like is not worn, the medium containing portion is in thermal contact with the outside air, a table, the floor, or the like (second heat source). In general, a certain temperature difference is created between the states in which the device is worn and in which it is not worn. The variable portion is deformed due to a temperature change every time the portable device (e.g., a portable telephone or a wristwatch) and the accessory are put on or are taken off, thereby deriving dynamic energy.
In a more specific thermal energy conversion method of the present invention, a heat converter is formed to have a sealed container for containing a heating medium that changes in volume in response to a temperature change, the sealed container has a medium containing portion that does not substantially change in capacity and a variable portion connected to the medium containing portion so as to be changeable in capacity. A first outer face portion to be contacted with a first heat source and a second outer face portion to be contacted with a second heat source, which changes in temperature to a greater degree than that of the first heat source, are formed on the periphery of the medium containing portion, and heat exchange efficiency between the outside and the medium containing portion via the first outer face portion is lower than the heat exchange efficiency between the outside and the medium containing portion via the second outer face portion.
For example, in the case of a portable device such as a wristwatch, or an accessory jewelry or the like), thermal conductivity of a portion of the case (e.g., a case back) having the first outer face portion in contact with the body and clothing is set to be lower than that of a portion of the case (e.g., the rim of a timepiece case) having the second outer face portion exposed to the outside air. This makes it possible to reliably transmit a change in outside air temperature into the medium containing portion, to allow the temperature of the medium containing portion to follow a change in the outside air temperature without being hindered by a steady thermal environment such as that of the body and clothing, and to derive energy with high efficiency.